The influence of scalar relativistic effect on the carbon monoxide adsorption onto small gold clusters

A comparative study between all-electron relativistic (AER) calculation and all-electron (AE) calculation on the carbon monoxide adsorption onto small gold clusters has been performed. Our results reveal that the AunCO cluster obtained by the AER method has shorter Au–C bond-length, longer C–O bond-length, larger binding energy and adsorption energy, higher VIP and VEA, greater charge transfers, higher vibrational frequency of the Au–C mode and lower vibrational frequency of the C–O mode. All these facts suggest that the scalar relativistic effect can strengthen the Au–C bond and weaken the C–O bond, appearing as shorter Au–C bond-length and longer C–O bond-length. It is believed that the scalar relativistic effect is favorable to the CO adsorption onto small gold clusters and the reactivity enhancement of CO molecule. Some further studies focused on the influence of scalar relativistic effect on the adsorption behavior of other small molecules onto gold clusters are necessary in the future.

► The scalar relativistic effect is favorable to the adsorption of CO molecule.
► The scalar relativistic effect promotes reactivity enhancement of CO molecule.
► The influence of scalar relativistic effect on the stabilization of adsorption can be observed.